1. Field of the Invention
This invention relates to an electronic component-mounting apparatus of a multi-function type for mounting electronic components supplied by using a pallet, on a circuit board.
2. Prior Art
Conventionally, an electronic component-mounting apparatus of this kind is known in which electronic components are directly fed to a main block thereof by bringing a pallet to a predetermined position in a pickup area of the main block, the pallet carrying thereon a single or a plurality of trays on which a lot of electronic components are juxtaposed (as disclosed e.g. in Japanese Laid-Open Patent Publication (Kokai) No. 3-257896). Such an electronic component-mounting apparatus includes an elevating mechanism for lifting and lowering pallets each carrying trays thereon to selectively guide the pallets to the level of a transfer path of the main block of the apparatus, a pallet guide device for drawing out the selected pallet from the elevating mechanism to the predetermined position in the pickup area along the transfer path, and a component-mounting device for picking up electronic components from the drawn-out pallet and mounting the same on a circuit board by using mounting heads thereof. Each pallet is lifted or lowered to the level of the transfer path by the elevating mechanism to be horizontally drawn out to the predetermined position in the pickup area by the pallet guide device.
The pallet guide device includes an engaging arm unit having an engaging arm rotatable to engage with a front edge of a pallet from above and a solenoid for actuating the engaging arm for engagement with and disengagement from the pallet, and a unit-moving device for moving the engaging arm unit forward and backward along the transfer path by using a motor as a drive source therefor. To draw out a pallet from the elevating mechanism, first the unit-moving device is driven to advance the engaging arm and the solenoid. When the engaging arm has reached the pallet, the engaging arm and the solenoid are stopped. Then, the solenoid is energized (or deenergized) to rotate the engaging arm to engage the same with the pallet. In this state, the engaging arm and the solenoid are moved backward to thereby draw out the pallet to the predetermined position in the pickup area. When a used pallet is returned to the elevating mechanism, the returning operation is carried out by completely reversing the above procedure.
The elevating mechanism and the pallet guide device are adjusted to operate at respective low speeds so as to prevent electronic components from leaving or jumping out of each component-holding groove in the tray. That is, each pallet is guided far more slowly than each mounting head carries out a sequence of operations required to pick up and mount an electronic component on the circuit board. When pallets are replaced, each mounting head has to wait until it is permitted to operate, resulting in an increase in tact time as a whole.
Further, in the case of the above-mentioned conventional electronic component-mounting apparatus, the pallet guide device is required to have two actuators (drive sources), i.e. a motor for the unit-moving device and a solenoid for the engaging arm unit, so that the conventional electronic component-mounting apparatus is complicated in construction. Moreover, the motor and the solenoid are driven in a manner interlocked with each other, which complicates the control of the apparatus.
It is a first object of the invention to provide an electronic component-mounting apparatus which is capable of minimizing a time period during which each mounting head has to wait to start operation.
It is a second object of the invention to provide a component-feeding device for an electronic component-mounting apparatus, which is capable of guiding a pallet to a pickup position by a simple construction and control system.
To attain the first object, according to a first aspect of the invention, there is provided an electronic component-mounting apparatus comprising:
a pallet-storing block for storing a plurality of pallets each carrying thereon a tray containing a large number of electronic components;
transfer means for moving a desired pallet selected from the pallets along a transfer path, in a manner such that the desired pallet is advanced to be introduced into a pickup area which extends to cover almost all of the transfer path or withdrawn from the pickup area toward the pallet-storing block;
component-mounting means for sequentially picking up desired electronic components from the desired pallet introduced into the pickup area and mounting the desired electronic components on a circuit board; and
control means for controlling the transfer means in a manner such that at least part of the desired pallet is moved to a desired position in the pickup area.
According to this electronic component-mounting apparatus, the pickup area from which electronic components are picked up is expanded to substantially the whole area of the transfer path, whereby it is possible to pick up electronic components from a pallet introduced to or positioned at any location on the transfer path the pallet is guided. Further, a desired pallet drawn out from the pallet-storing block can be introduced to a desired position in the transfer path, which makes it possible to introduce the desired pallet to a suitable position in the above transfer path, while taking into account a speed at which the component-mounting means carries out its electronic component-pickup and mounting operations such that the electronic component-mounting means does not have to wait for the desired pallet to be brought to a proper or predetermined position.
Preferably, the component-mounting means includes a mounting head,
the mounting head sequentially picking up and mounting the desired electronic components on the circuit board.
According to this electronic component-mounting apparatus, a desired pallet drawn out from the pallet storing block can be introduced to a desired position in the transfer path, which makes it possible to introduce the desired pallet to a suitable position in the above passage, while taking into account a speed at which the mounting head carries out its electronic component-pickup and mounting operations such that the mounting head does not have to wait for the desired pallet to be brought to a proper or predetermined position.
More preferably, the electronic components are juxtaposed within the tray in a plurality of rows,
the control means controlling the transfer means in a manner such that the desired pallet is stepwise advanced to thereby sequentially introduce each of the rows into the pickup area,
the mounting head picking up desired electronic components from the each of the rows, as the each of the rows is sequentially brought into the pickup area.
According to this preferred embodiment, electronic components carried on a pallet can be sequentially picked up as each of rows of electronic components is sequentially brought into the pickup area, whereby it is possible to reduce the traveling distance of each pallet. Although this increases the traveling distance of the mounting head, the mounting head travels much faster than the pallet and hence it is possible to reduce the tact time (mounting time per circuit board) as a whole.
Alternatively, the control means controls the transfer means in a manner such that the desired pallet is advanced along the transfer path to a position at which the desired pallet is not completely drawn out of the pallet-storing block,
the mounting head sequentially picking up and mounting the desired electronic components on the circuit board when the desired pallet is in the position.
According to this preferred embodiment, the traveling distance of the desired pallet can be reduced similarly to the above embodiment, which makes it possible to reduce the tact time as a whole.
Further preferably, the electronic components are juxtaposed in the tray in a plurality of rows,
the control means controlling the transfer means in a manner such that whenever the mounting head picks up a last electronic component to be picked up from each of the rows, the desired pallet is stepwise advanced to introduce another row of the rows into the pickup area.
Alternatively, the control means controls the transfer means in a manner such that after the desired pallet is moved to a position substantially closest to a position to which the circuit board is introduced, the desired pallet is moved by a slight distance so as to minimize a distance over which the mounting head is required to travel to pick up and mount each of the desired electronic components on the circuit board.
According to this preferred embodiment, the traveling distance of the mounting head is always minimized and hence it is possible to reduce the tact time. This control method is useful especially when pallets are not frequently replaced.
Alternatively, the electronic components are juxtaposed in the tray in a plurality of rows,
the control means controlling the transfer means in a manner such that the desired pallet is first advanced to bring all of the rows of the electronic components into the pickup area, and then, starting with a rear end one of the rows, whenever the mounting head picks up a last electronic component to be picked up from each of the rows, the desired pallet is stepwise withdrawn toward the pallet-storing block.
Alternatively, the electronic components are juxtaposed in the tray in a plurality of rows,
the control means controlling the transfer means in a manner such that whenever the mounting head picks up a last electronic component to be picked up from each of the rows introduced into the pickup area, the desired pallet is stepwise advanced to introduce another row of the rows into the pickup area, and that after the desired pallet is moved to a position substantially closest to a position to which the circuit board is introduced, the desired pallet is moved by a slight distance so as to minimize a distance over which the mounting head is required to travel to pick up and mount each of desired electronic components, and that before all electronic components to be mounted on the circuit boards are picked up from the desired pallet, whenever the mounting head picks up a last electronic component to be picked up from each of rows of remaining ones of the electronic components to be mounted, the pallet is stepwise withdrawn toward the pallet-storing block.
Preferably, the control means controls the transfer means in a manner such that the desired pallet is moved while the mounting head is operating to pick up and mount each of the desired electronic components.
According to this preferred embodiment, the operation of the mounting head and the transfer of the desired pallet can be systematically carried out and hence this control method is useful in reducing the tact time especially when pallets are frequently replaced.
Preferably, the pallet-storing block includes a pallet storage device for storing the pallets in a vertically spaced manner,
the transfer means including a lift mechanism for vertically lifting and lowering the pallet storage device in a manner such that the desired pallet is brought to a level identical to a level of the transfer path.
To attain the first object, according to a second aspect of the invention, there is provided an electronic component-mounting apparatus comprising:
a pair of pallet-storing blocks for each storing a plurality of pallets each carrying thereon a tray containing a large number of electronic components, the pallet-storing blocks being arranged on respective opposite ends of a transfer path along which desired pallets drawn out respectively from the pallet-storing blocks are moved;
transfer means for moving the desired pallets along the transfer path in a manner such that each of the desired pallets is advanced to be brought into a pickup area or withdrawn from the pickup area toward the pallet-storing block;
component-mounting means for sequentially picking up desired electronic components from the each of the desired pallets brought into the pickup area and mounting the desired electronic components on a circuit board; and
control means for controlling the transfer means in a manner such that the desired pallets are alternately introduced into the pickup area, and while one of the desired pallets has been introduced into the pickup area, another of the desired pallets is made on standby in the vicinity of the one of the desired pallets.
According to this preferred embodiment, pallets are alternately guided to the pickup area to cause one of the pallets to wait in the vicinity of the other pallet, whereby even when the pickup area is narrow and located far from the pallet-storing block, it is possible to reduce the time required for replacing pallets.
Preferably, the transfer means includes an engagement unit that carries out engagement with and disengagement from the desired pallet, and driving means for moving the engagement unit along the transfer path in a manner such that the engagement unit is advanced to the desired pallet or withdrawn from the desired pallet.
More preferably, the engagement unit comprises engaging arm means formed in a manner such that the engaging arm means is capable of engaging with and disengaging from each of the pallets, and conversion means for converting a driving force applied to the engagement unit by the driving means for urging the engagement unit toward the desired pallet into operations for the engagement with and disengagement from the desired pallet.
According to this preferred embodiment, the driving force of the driving means for drawing out and returning (moving forward and backward) the desired pallet can be converted by the conversion means into operation of the engaging arm means. Therefore, it is possible to omit a drive source dedicatedly provided for causing the engaging arm means to carry out the engaging and disengaging operations.
Further preferably, the conversion means comprises an arm support block for supporting the engaging arm means in a manner such that the engaging arm means is capable of engaging with and disengaging from each of the pallets, a body supporting the arm support block in a manner such that the arm support block is capable of moving along the transfer path relative to the body, the body being moved by the driving means in unison with the arm support block, a stopper for stopping the arm support block from advancing when the arm support block has moved in unison with the body to an engaging operation position, an actuating member fixed to the body, the actuating member causing the engaging arm means to carry out an operation for the engagement as the body is further advanced with respect to the arm support block, and carry out an operation for the disengagement as the body is withdrawn, in a state in which the arm support block is in stoppage.
According to this preferred embodiment, when the driving means causes the engagement unit i.e. the engaging arm means and the conversion means to advance toward the pallet-storing block, the advance of the arm support block is stopped at the engaging operation position by the stopper, while only the body is advanced in an overrunning manner. At this time point, the actuating member advancing in unison with the body causes the engaging arm means stopped at the engaging operation position to carry out the disengaging operation for disengaging from a pallet. Assuming that the engaging arm has a used pallet engaged therewith, the used pallet is returned to the pallet-storing block by this disengaging operation. Next, the withdrawal of the body starts. In accordance with the withdrawal of the body, the actuating member causes the engaging arm means stopped at the engaging operation position to carry out the engaging operation for engaging with a desired pallet. When the body continues to withdraw, the engaging arm means also starts moving backward to draw out the pallet. That is, the driving force of the driving means for drawing out and returning (moving forward and backward) the desired pallet can be converted by the conversion means into operation of the engaging arm means. Therefore, it is possible to omit a drive source dedicatedly provided for causing the engaging arm means to carry out the engaging and disengaging operations.
Further preferably, the engaging arm means comprises a pair of engaging arms arranged at respective locations opposed to each other in a direction transverse to the transfer path.
Still more preferably, the engaging arms each comprise an engaging block for engagement with the each of the pallets, an abutment portion against which the actuating member abuts to apply the driving force of the driving means thereto, and a connecting portion integrally formed with the engaging block and the abutment portion, the arm support block including a pivot for pivotally supporting the connecting portion, and urging means for urging the engagement block in an engaging direction.
Still further preferably, the urging means is a spring interposed between the pair of engaging arms.
Still more preferably, the transfer means includes guide means for supporting the desired pallet in a manner such that the desired pallet is movable along the transfer path.
Still further preferably, the guide means includes a plurality of guide blocks located at different levels, the engaging block comprises a plurality of engaging portions each formed at levels identical to the different levels of the guide blocks, respectively.
To attain the second object, according to a third aspect of the invention, there is provided a component-feeding device for an electronic component-mounting apparatus, comprising:
a pallet-storing block for storing a plurality of pallets each carrying thereon a tray containing a large number of electronic components; and
transfer means for moving a desired pallet selected from the pallets along a transfer path, in a manner such that the desired pallet is advanced to a pickup position or withdrawn from the pickup position toward the pallet-storing block,
the transfer means including an engagement unit that carries out engagement with and disengagement from the desired pallet, and driving means for moving the engagement unit along the transfer path in a manner such that the engagement unit is advanced to the desired pallet ox withdrawn from the desired pallet,
the engagement unit comprising engaging arm means formed in a manner such that the engaging arm means is capable of engaging with and disengaging from each of the pallets, and conversion means for converting a driving force applied to the engagement unit by the driving means for urging the engagement unit toward the desired pallet into operations for the engagement with and disengagement from the desired pallet.
According to this component-feeding device, the driving force of the driving means for drawing out returning (moving forward and backward) the desired pallet can be converted by the conversion means into operation of the engaging arm means. Therefore, it is possible to omit a drive source dedicatedly provided for causing the engaging arm means to carry out the engaging and disengaging operations.
Preferably, the conversion means comprises an arm support block for supporting the engaging arm means in a manner such that the engaging arm means is capable of engaging with and disengaging from each of the pallets, a body supporting the arm support block in a manner such that the arm support block is capable of moving along the transfer path relative to the body, the body being moved by the driving means in unison with the arm support block, a stopper for stopping the arm support block from advancing when the arm support block has moved in unison with the body to an engaging operation position, an actuating member fixed to the body, the actuating member causing the engaging arm means to carry out an operation for the engagement as the body is further advanced with respect to the arm support block, and carry out an operation for the disengagement as the body is withdrawn, in a state in which the arm support block is in stoppage.
According to this preferred embodiment, when the driving means causes the engagement unit i.e. the engaging arm means and the conversion means to advance toward the pallet-storing block, the advance of the arm support block is stopped at the engaging operation position by the stopper, while only the body is advanced in an overrunning manner. At this time point, the actuating member advancing in unison with the body causes the engaging arm means stopped at the engaging operation position to carry out the disengaging operation for disengaging from a pallet. Assuming that the engaging arm has a used pallet engaged therewith, the used pallet is returned to the pallet-storing block by this disengaging operation. Next, the withdrawal of the body starts. In accordance with the withdrawal of the body, the actuating member causes the engaging arm means stopped at the engaging operation position to carry out the engaging operation for engaging with a desired pallet. When the body continues to withdraw, the engaging arm means also starts moving backward to draw out the pallet. That is, the driving force of the driving means for drawing out and returning (moving forward and backward) the desired pallet can be converted by the conversion means into operation of the engaging arm means. Therefore, it is possible to omit a drive source dedicatedly provided for causing the engaging arm means to carry out the engaging and disengaging operations.
The above and other objects, features, and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.